The exterior cladding and balconies at the 16-level Victopia apartment block in central Auckland are suffering weathertightness defects, according to the lawyer representing owners bringing New Zealand's biggest leaky building litigation.

Gareth Lewis, the Grimshaw & Co lawyer acting for Body Corporate 346799 which is taking the $40 million action, told Justice Susan Thomas in the High Court at Auckland of issues with these two parts of the high-rise block at 135 Victoria Street West.

He showed the court photographs of the exterior building cladding and pointed out how sheets of materials had "dislodgement" or cracks and splits in them.

The cladding in the building on the Nelson St corner was a pressure-equalised system, Lewis told the court.

He then showed photographs of tiles on balconies in the building where he indicated there were also significant issues. Every apartment in the block has a balcony and on level 14, units have two balconies, he said.

Expert investigations were carried out into why these aspects of the block had failed, he said.

"The waterproof membrane has deteriorated," Lewis said, "and is either soft, mushy or tacky. It has not properly bonded and it had ceased to act as an effective waterproof membrane in that it would not repel water," Lewis said in his opening submissions.

"It is common ground that this condition is not what it should be. It's not supposed to fall apart like this. As a result of the failure, balcony tiles became lose, lifted, there are cracks in numerous tiles, the grouting has become dislodged and moisture has become trapped," Lewis said, describing how this was apparent when people walked on the balconies.

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She also asked if the balcony conditions posed any danger or created any safety issues, but Lewis said this was not the case.

The waterproof membrane has deteriorated and is either soft, mushy or tacky. It has not properly bonded and it had ceased to act as an effective waterproof membrane in that it would not repel water.

Gareth Lewis, Grimshaw & Co lawyer

Lewis this morning called expert witness Colin Lim, a specialist facade engineer of AECOM in Sydney and a lecturer at the University of Technology Sydney. Lim told the court how he had 30 years experience in the building industry, working in Australia and Asia.

He investigated issues at Victopia and said the cladding system in blocks like that was a rain screen and there could not be any cracks in that material or water would get in. He likened the cladding to a rain coat.

Victopia had three types of cladding systems, Lim said, covering different elevations of the block.

Cladding panels were erected on the site "almost like Lego blocks", he said.

The body corporate is suing developer KNZ International (formerly named Ganda Development Co Ltd and Dae Ju Developments Co Ltd), construction business Brookfield Multiplex, Auckland Council and Bostik New Zealand.

It reached a settlement with Facade Design Services before the hearing started, Lewis told the court yesterday.

The case is continuing and the defendants are yet to begin opening submissions or calling their witnesses.

However, Lewis said outside court yesterday that KNZ was not represented in the case by legal counsel.